1. Field of the Invention
The present invention relates to a plastic container for containing a liquid, such as toilet water or soy source and, more particularly, to a plastic container for containing a refill and a method of manufacturing such a plastic container for containing a refill.
2. Description of the Related Art
A known cartridge, i.e., a plastic container, capable of sealing a fluidic material, such as an adhesive, therein is formed by insert injection molding using a mold.
FIG. 5 shows a known cartridge 101 formed by insert injection molding using a mold. The cartridge 101 has a tube 102 of a plastic laminate, a bottom molded part 103 joined to a lower end part of the tube 102, a top molded part 104 joined to an upper end part of the tube 102, and a bottom member 106 of a plastic laminate bonded to the lower end of the bottom molded part 103. When forming the cartridge 101 by insert injection molding, a mold inserted in the tube 102 must be capable of being extracted from the tube 102. Therefore the inner circumference of the tube 102 must be smooth and must not have irregularities and the tube 102 must be slightly tapered from its lower end on the side of the bottom molded part 103 toward its upper end on the side of the top molded part 104.
FIG. 6 is a sectional view of assistance in explaining a method of manufacturing the known cartridge 101. The tube 102 has the shape of a tube having opposite open ends. The tube 102 is put on a mandrel 100, i.e., a metal core, tapered from its lower end toward its upper end. When the mandrel 100 holding the tube 102 is set in a mold 111, a molding cavity 103a corresponding to the annular bottom molded part 103 of the cartridge 101 is formed around the lower end part of the tube 102, and a molding cavity 104a corresponding to the top molded part 104 is formed around the upper end part of the tube 102. The molding cavities 103a and 104a are connected to a runner 112 formed in the mold 111. After the tube 102 has been thus set in the mold 111, a molten synthetic resin, such as a molten polyethylene resin through a gate 113 formed in the mold 111 and the runner 112 into the molding cavities 103a and 104a by an insert injection molding means. Thus, a body having the tube 102 provided with an annular bottom molded part 103 on its lower end part and a top molded part 104 joined to the upper end of the tube 102, and having an open bottom end is formed.
Since the cartridge 101 is formed by insert injection molding using the mold, the bottom molded part 103 must be formed in an annular shape on the lower end part of the tube 102 when the top molded part 104 having an outlet opening is joined to the upper end of part of the tube 102. Since the bottom molded part 103 is open, the bottom member 106 of the plastic laminate similar to that forming the tube 102 must be joined to the lower end of the bottom molded part 103 by heat sealing.
Since the bottom member 106 of the plastic laminate is joined to the bottom molded part 103 of the cartridge 101, gaps are liable to be formed in the joint 106a of the bottom molded part 103 and the bottom member 106 if the rigidity of the bottom molded part 103 is insufficient and the bottom molded part 103 is loaded during transportation, and the cartridge 101 falls down easily. If the bottom member 106 of the plastic laminate is bonded unsatisfactorily to the bottom molded part 103, the contents of the cartridge 101 leaks through faultily bonded parts of the joint of the bottom member 106 and the bottom molded part 103. Even if the bottom member 106 is bonded closely to the bottom molded part 103, the bottom member 106 of the plastic laminate is broken with a sharp point and the contents leaks or the barrier property of the bottom member 106 is deteriorated.
The present invention has been made in view of the foregoing problems and it is therefore an object of the present invention to provide a plastic container having a rigid bottom wall formed by molding a plastic material and resistant to the accidental formation of holes therein and the resultant leakage of the contents of the plastic container.
A plastic container according to one aspect of the present invention comprises a tube of a plastic laminate, a bottom wall formed so as to be joined to the inner circumference of a lower end part of the tube by an insert injection molding process, a hoop formed on the outer circumference of an upper end part of the tube by an insert injection molding process, and a top cover provided with a spout and bonded to the upper end surface of the hoop.
Since the bottom wall is joined to the inner circumference of the lower end part of the tube and the hoop is joined to the outer circumference of the upper end part of the tube, a mandrel inserted in the tube for insert injection molding can be extracted from the tube. Thus, the bottom wall and the hoop of the plastic container can be formed integrally with the tube by the insert injection molding process to complete the plastic container. The bottom wall thus formed by the insert injection molding process is more resistant to breakage than the bottom wall of the plastic laminate.
In this invention, the term of xe2x80x9cinsert injection molding meansxe2x80x9d is used in the sense that the plastic container is manufactured in the steps of:
forming the tube; putting the tube on a mandrel; inserting the mandrel holding the tube in a mold; injecting a molten resin into the first and the second cavity to form the bottom wall and the hoop; and bonding the top cover.